This invention relates to an industrial robot having a plurality of axes of movement and a fixed focus toolholder head.
Although the robot according to the present invention is designed as a multifunctional working machine it is particularly adapted for use in Tungsten Inert Gas, Metal Inert Gas, and Metal Active Gas, hereinafter referred to as TIG, MIG and MAG arc welding, respectively.
TIG, MIG and MAG welding robots are known in which the welding torch is supported by a toolholder having two or more degrees of freedom of movement so that the torch tip carries out a rotary movement in the space. As the welding torch is in a fixed position with respect to the toolholder that supports it, considerable problems are encountered in programming the movements of the robot when it is necessary to adjust the focus of the welding torch during its operation to achieve best results. In fact, any modification of the path or location of the welding torch involves a more general modification of the attitude of the robot including a correction of the movement of other axes which are not those defining the movement of the toolholder head. Even for making a minute correction in the location of the welding torch such programming of the robot is an extremely difficult and complex operation.
It is an object of the present invention to eliminate these drawbacks and particularly to reduce the complexity of programming by providing a robot having a plurality of axes of movement so as to permit the location of the welding torch to be modified or corrected only by rotary or angular movements of the head of the robot while constantly maintaining the welding torch in centered position without adjusting the other axes of movement of the robot or its overall attitude. This ability to maintain the tool holder and thus the welding torch as constantly centered while permitting the toolholder to be moved in accordance with its degrees of freedom is referred to herein as maintaining a "fixed focus" or having a "fixed point of focus".